Below is a 8th library for an old school style state machine based validator for numeric strings. Using RegEx is not always the best tool for the job when simple state machine will do.

Includes words that test if string is a valid int or float and word that test if string is a valid number and also returns type of number.

```
\
\ validate.8th
\
\ Simple state machine based string validator for numbers.
\
ns?
ns: validate
0 constant INTEGER
1 constant FLOAT
private
32 constant SPACE
09 constant TAB
\ status
0 constant EMPTY
1 constant PARTIAL-FAIL
2 constant PARTIAL-OK
3 constant OK
4 constant ERROR
\ state
0 constant S0
1 constant IPART
2 constant FPART
3 constant ESIGN
4 constant EPART
: make-dword \ lword hword -- dword
0xffff n:band 16 n:shl swap
0xffff n:band
n:bor ;
: s1
IPART "state" t:!
PARTIAL-FAIL "status" t:! ;
: s2
IPART "state" t:!
OK "status" t:! ;
: s3
FPART "state" t:!
PARTIAL-FAIL "status" t:! ;
: s4
ESIGN "state" t:!
PARTIAL-OK "status" t:! ;
: s5
OK "status" t:! ;
: s6
FPART "state" t:!
PARTIAL-FAIL "status" t:! ;
: s7
ESIGN "state" t:!
PARTIAL-OK "status" t:! ;
: s8
OK "status" t:! ;
: s9
ESIGN "state" t:!
PARTIAL-OK "status" t:! ;
: s10
EPART "state" t:!
PARTIAL-FAIL "status" t:! ;
: s11
EPART "state" t:! ;
: s12
OK "status" t:! ;
[ ( ` SPACE S0 make-dword ` "dword" t:@ n:= ), ' noop,
( ` TAB S0 make-dword ` "dword" t:@ n:= ), ' noop,
( ` '+ S0 make-dword ` "dword" t:@ n:= ), ' s1,
( ` '- S0 make-dword ` "dword" t:@ n:= ), ' s1,
( ` '0 S0 make-dword ` "dword" t:@ n:= ), ' s2,
( ` '1 S0 make-dword ` "dword" t:@ n:= ), ' s2,
( ` '2 S0 make-dword ` "dword" t:@ n:= ), ' s2,
( ` '3 S0 make-dword ` "dword" t:@ n:= ), ' s2,
( ` '4 S0 make-dword ` "dword" t:@ n:= ), ' s2,
( ` '5 S0 make-dword ` "dword" t:@ n:= ), ' s2,
( ` '6 S0 make-dword ` "dword" t:@ n:= ), ' s2,
( ` '7 S0 make-dword ` "dword" t:@ n:= ), ' s2,
( ` '8 S0 make-dword ` "dword" t:@ n:= ), ' s2,
( ` '9 S0 make-dword ` "dword" t:@ n:= ), ' s2,
( ` '. S0 make-dword ` "dword" t:@ n:= ), ' s3,
( ` 'e S0 make-dword ` "dword" t:@ n:= ), ' s4,
( ` 'E S0 make-dword ` "dword" t:@ n:= ), ' s4,
( ` '0 IPART make-dword ` "dword" t:@ n:= ), ' s5,
( ` '1 IPART make-dword ` "dword" t:@ n:= ), ' s5,
( ` '2 IPART make-dword ` "dword" t:@ n:= ), ' s5,
( ` '3 IPART make-dword ` "dword" t:@ n:= ), ' s5,
( ` '4 IPART make-dword ` "dword" t:@ n:= ), ' s5,
( ` '5 IPART make-dword ` "dword" t:@ n:= ), ' s5,
( ` '6 IPART make-dword ` "dword" t:@ n:= ), ' s5,
( ` '7 IPART make-dword ` "dword" t:@ n:= ), ' s5,
( ` '8 IPART make-dword ` "dword" t:@ n:= ), ' s5,
( ` '9 IPART make-dword ` "dword" t:@ n:= ), ' s5,
( ` '. IPART make-dword ` "dword" t:@ n:= ), ' s6,
( ` 'e IPART make-dword ` "dword" t:@ n:= ), ' s7,
( ` 'E IPART make-dword ` "dword" t:@ n:= ), ' s7,
( ` '0 FPART make-dword ` "dword" t:@ n:= ), ' s8,
( ` '1 FPART make-dword ` "dword" t:@ n:= ), ' s8,
( ` '2 FPART make-dword ` "dword" t:@ n:= ), ' s8,
( ` '3 FPART make-dword ` "dword" t:@ n:= ), ' s8,
( ` '4 FPART make-dword ` "dword" t:@ n:= ), ' s8,
( ` '5 FPART make-dword ` "dword" t:@ n:= ), ' s8,
( ` '6 FPART make-dword ` "dword" t:@ n:= ), ' s8,
( ` '7 FPART make-dword ` "dword" t:@ n:= ), ' s8,
( ` '8 FPART make-dword ` "dword" t:@ n:= ), ' s8,
( ` '9 FPART make-dword ` "dword" t:@ n:= ), ' s8,
( ` 'e FPART make-dword ` "dword" t:@ n:= ), ' s9,
( ` 'E FPART make-dword ` "dword" t:@ n:= ), ' s9,
( ` '+ ESIGN make-dword ` "dword" t:@ n:= ), ' s10,
( ` '- ESIGN make-dword ` "dword" t:@ n:= ), ' s10,
( ` '0 ESIGN make-dword ` "dword" t:@ n:= ), ' s11,
( ` '1 ESIGN make-dword ` "dword" t:@ n:= ), ' s11,
( ` '2 ESIGN make-dword ` "dword" t:@ n:= ), ' s11,
( ` '3 ESIGN make-dword ` "dword" t:@ n:= ), ' s11,
( ` '4 ESIGN make-dword ` "dword" t:@ n:= ), ' s11,
( ` '5 ESIGN make-dword ` "dword" t:@ n:= ), ' s11,
( ` '6 ESIGN make-dword ` "dword" t:@ n:= ), ' s11,
( ` '7 ESIGN make-dword ` "dword" t:@ n:= ), ' s11,
( ` '8 ESIGN make-dword ` "dword" t:@ n:= ), ' s11,
( ` '9 ESIGN make-dword ` "dword" t:@ n:= ), ' s11,
( ` '0 EPART make-dword ` "dword" t:@ n:= ), ' s12,
( ` '1 EPART make-dword ` "dword" t:@ n:= ), ' s12,
( ` '2 EPART make-dword ` "dword" t:@ n:= ), ' s12,
( ` '3 EPART make-dword ` "dword" t:@ n:= ), ' s12,
( ` '4 EPART make-dword ` "dword" t:@ n:= ), ' s12,
( ` '5 EPART make-dword ` "dword" t:@ n:= ), ' s12,
( ` '6 EPART make-dword ` "dword" t:@ n:= ), ' s12,
( ` '7 EPART make-dword ` "dword" t:@ n:= ), ' s12,
( ` '8 EPART make-dword ` "dword" t:@ n:= ), ' s12,
( ` '9 EPART make-dword ` "dword" t:@ n:= ), ' s12,
( ERROR "status" t:! ) ] var, state-table
: number
S0 "state" t:!
EMPTY "status" t:!
( "status" t:@ ERROR n:= if
break
2drop
else
nip "state" t:@ make-dword "dword" t:! state-table @ a:when
then ) s:each
"status" t:@ "state" t:@ make-dword
[ ( ` OK IPART make-dword ` over n:= ), ( validate:INTEGER ),
( ` OK FPART make-dword ` over n:= ), ( validate:FLOAT ),
( ` PARTIAL-OK FPART make-dword ` over n:= ), ( validate:FLOAT ),
( ` PARTIAL-OK ESIGN make-dword ` over n:= ), ( validate:FLOAT ),
( ` OK EPART make-dword ` over n:= ), ( validate:FLOAT ),
( ` PARTIAL-OK EPART make-dword ` over n:= ), ( validate:FLOAT ),
( null ) ] a:when nip ;
public
: int? \ s -- T
#p:number null? if
drop false
else
INTEGER n:=
then ;
: float? \ s -- T
#p:number null? if
drop false
else
FLOAT n:=
then ;
: num? \ s -- n|null T
#p:number null? if
false
else
true
then ;
ns
```